Helen Springs Amethyst Deposit, Helen Springs Station, Barkly Region, Northern Territory, Australiai

Regional Level Types
Helen Springs Amethyst Deposit	Deposit
Helen Springs Station	- not defined -
Barkly Region	Region
Northern Territory	Territory
Australia	Country

Located immediately south-east of the Helen Springs Station turn-off from the Stuart Highway. Renner Springs is 18 kilometres to the north, and Tennant Creek 140 kilometres to the south.

Despite being very accessible to the highway, only one specimen has been seen for public sale in the last ten years. This was described as amethystine, hematite, quartz, jasper, only coming to light when polished showing translucent amethystine, with much hematite giving a 3D effect under the polished surface. Other specimens may exist in private collections. The lack of specimens compared to the Wave Hill area, may possibly indicate a lack of specimen grade material on the surface.

In 1967, the lessee was J. Pollard, who called in government geologists to assess the economic worth of the deposit. Instead they focussed largely on the surrounding geology.

Underlying rocks are gently dipping, laminated sandstones of the Tomkinson Creek Beds, with marked colour changes. Above this is vesicular basalt and upper andesite flows, with vugs containing quartz, with minor amethyst, and smokey quartz, sometimes chlorite encrusted. There are five distinct basalt flows, each with varying amounts of amygdaloidal quartz, the thickest just under the andesite capping, up to 4 feet thick.

The contact between the two rock types may contain small patches of chalcedony in joint plains, with small hematite veinlets. The quartz veins may have banding, with translucent euhedral quartz forming an outer layer, with an amethyst and smokey quartz core. Small gem quality amethyst crystals in one layer have been reported, up to three quarters of an inch long, and sporadically elsewhere. Diagrams in the source indicate the material is at the northern end of a north-south ridge, and half-way up the 40 metre high ridge.

Other Regions, Features and Areas containing this locality

References